| Abstract: | Anacystis nidulans (Richt.) Drouet & Daily (UTEX 625), grown in batch culture with 0.5% CO2 in air, was supplied with chloride labelled with 36Cl in light and dark. Uptake in light was stimulated relative to uptake in darkness. A single transport system for Cl? with an apparent Km for Cl? of 0.14 mM was identified. Chloride in the cells reached a maximum value after 30–50 min at 25 C. At this point the internal Cl? concentration was calculated to be 60-fold the external (0.1 mM) in light and 37-fold in darkness. DCMU (3-[3,4-dichlorophenyl]–1, 1-dime-thylurea), at concentrations which abolished photosynthetic O2 evolution did not inhibit Cl? uptake in light. Carbonyl cyanide m-chlorophenyl hydrazone (CCCP), at uncoupling concentrations for photosynthesis and dark respiration, strongly inhibited Cl? uptake in light and darkness. N,N'-dicyclohexyl carbodiimide (DCCD), an energy transfer inhibitor, inhibited light Cl? uptake more slowly than photosynthesis but had no effect on dark Cl? uptake. It is concluded that Cl? uptake in A. nidulans was active in light and darkness, and that ATP was the probable energy source for transport. |
